Device for initiation of the printing action on a high-speed printer



United States Patent [72] Inventors Max Oberholzer, Liebefeld,

near Bern; Robert Locher, Schonbuhl; Heinz Brechbiihl, Bern,

.fiw tz r anst M [21] Appl. No. 698,481 [22] Filed Jan. 17, 1968 [45]Patented Sept. 15, 1970 [73] Assignee Hasler A.G.,

Bern, Switzerland,

a company of Switzerland [32] Priority Jan. 19, 1967 [3 3] Switzerland[31] No. 750/67 [54] DEVICE FOR INITIATION OF THE PRINTING ACTION ON AHIGH-SPEED PRINTER 6 Claims, 4 Drawing Figs. 52 U.S.Cl 101/93 [51] Int.Cl B41j 9/14, B41 j 9/16 [50] FieldofSearch 101/93,9l,

[56] References Cited UNITED STATES PATENTS 2,766,686 10/1956 Fomenko etal.

2,893,313 7/1959 Pekar et al 2,895,411 7/1959 Demer et al.

3,043,213 7/1962 Donabin 3,128,694 4/1964 Kittler 3,351,007 11/1967Poland Primary ExaminerWilliam B. Penn AttorneyMichael S. StrikerABSTRACT: A high-speed printer including a rotating type drum, aplurality of strikers arranged to press, when actuated, a recordingmedium against a character on the periphery of the type drum, andactuating means for actuating selected strikers and including a cam drumhaving cams selectively movable between an active and an inactiveposition to actuate in the active position a selected striker.

IHI llllll 111 Patented Sept. 15, 1970 3,528,368

Sheet 1 of2 FIG.|

Patented Sept. 15, 1970 3,528,368

sneet 2 or2 DEVICE FOR INITIATION OF THE PRINTING ACTION ON A HIGH-SPEEDPRINTER The present invention relates to an improved device forinitiation of the printing action on a high-speed printer.

In high-speed printers constructed for high working speeds, continuouslyrevolving type drums are frequently employed, whereof the lengthcorresponds to the line width of the paper to be printed. A thrusthammer or striker for each .print or impression point, is situatedadjacent the peripheryof the type drum. To print the characters, thesestrikers are impelled against a paper positioned between the type drumand the strikers. The strikers are so controlled, respectivelytriggered, in a timed sequence, that a full line is printed after eachrevolution of the type drum. The correct choice and co-ordination to theangular position of the type drum is established by means of anelectronic control system which at the same time also controls the paperfeed.

Stringent requirements are applied with respect to the driving systemfor the strikers of such printing mechanisms, since the impulsionfrequency is very high, and a short period of contact between thestriker and the paper must be obtained while the required impact energymust be generated. The division of these driving systems should moreoverbe kept sufficiently small so that impression points may be placed oneach inch of width of the recording paper.

Electromagnetic driving systems are employed for accelerating thestrikers in numerous known high-speed printers. The efficiency of thesedevices, however, is low, since it is difficult to generate the speedand momentum required for the strikers by means of electromagnets.Maintenance of the precise printing instant is also extremely difficultin such driving systems.

A triggering device is already known, in which a so-called impact wheelrunning synchronously with the type drum is employed as a mechanicalenergy storage device for accelerating the strikers. In the same, acoupling element is inserted from the outside at the desired instant,under control of a magnetic system, into the impact wheel, which causesthe initiation of the printing action, inasmuch as a tooth of the impactwheel or gear is coupled with the striker and the impact wheel impartsthe required energy to the striker.

In this initiating device, the coupling element is situated outside theenergy storage device, i.e. is structurally separate from the same.

In the device according to the present invention for initiation of theprinting action on a high-speed printer, the coupling element istransferred into the energy store, thereby obtaining a simple structurereliable in operation. This device is characterized in that parallel tothe type drum a continuously revolving cam drum is provided, in whichseveral cams are housed for each printing point, which may optionally bebrought into the operating position by means of a magnetic systemsituated on the periphery of the cam drum, in which position theyoperate the strikers and thus initiate the printing action.

The characteristic features of the invention are fully disclosed in thefollowing description and the accompanying drawing of a preferredembodiment of the invention in which:

FIG. 1 is a schematic perspective view of the device according to thepresent invention; and

FIGS. 2-4 are side views showing various elements of the device insuccessive positions.

In the initiating and printing device drawn diagrammatically and inperspective, the continuously revolving type drum built up from separatetype discs, is marked I. On the periphery of each type disc areprovided, for example, characters 2 for printing and an unoccupied spacerunning past the striker during the period of paper feed.

Axially parallel to the type drum 1 is situated the equally continuouslyrevolving cam drum 3, which is built up from separate cam discs 4. Thecams for two consecutive impression points positioned adjacently in theimpression line, are slidably arranged in radially extending grooves 14formed in opposite end faces of the cam discs 4. In the example of theillustrated embodiment, nine cams 5 are incorporated per impressionpoint or for each disc of the type drum, of which only four are showncompletely in the drawing for the first impression point.

Since the number of characters 2 provided per impression point does notcorrespond to the number of cams 5, while a cam 5 must be co-ordinatedwith each character 2, the required correction is obtained by thetransmission ratio between the type drum 1 and the cam drum 3, the camdrum 3 rotating correspondingly faster.

An electrically controllable coil 6 of an electro-magnet is incorporatedon the outer periphery of the cam'drum 3 for each impression point. Inorder that the lateral distance between one impression point and thenext may be kept as small as possible, the coils 6 are positionedstaggered relative to each other on the periphery of the cam drum. Byenergizing the coil 6 of a-respective electromagnet, the cams 5 mayselectively be moved radially outwardly to their operating position.

Ahead of each coil 6, in direction of rotation of the drum 3, issituated a return or restoring (50g 7 having a cam surface 7a, by meansof which the cam 5 drawn out by the coil 6 is pushed back into theinitial position. The corresponding coil 6 is ac-- .tivated by means ofan electronic selection system, to initiate the printing action at animpression point. If the cadencer signal corresponds to the input signalof the required character, the coil 6 is energized during the time inwhich the brush 8 of the cadencer rotating with the type drum 1 brushesover a contact track 9a of the contacter disc 9, and the cam 5 situatedunder the pole piece 6a at this instant is moved radially outwardly intothe operating position.

During continued rotation of the cam drum 1 in the direction shown bythe arrow, the radially outwardly moved cam 5 strikes the correspondingstriker segment 10 of a set of striker elements tumably mounted on a pin-15 and whose lower extremities are situated barely above the cam drum3. The upper extremity of the struck striker segment is thereby flungagainst the type drum 1 respectively against the recording paper 13situated between the striker segment and the type drum.

Since the weight of the striker segment 10 is relatively low, themechanical energy stored in the cam drum 3, on impact of a cam,engenders a powerful acceleration of the striker segment in thedirection toward the type drum. The impression is produced by impact ofthe striker segment 10 on the recording paper 13 respectively the typedrum 1.

After impact on the type drum 1, the striker segment 10 rebounds, and isheld in the initial position by a spring 16 fastened at opposite ends toa fixed pin 17 and to the striker segment against a damping element 18.

Before the radially outwardly moved cam 5 reaches its coil 6 againduring further rotation of the cam drum 3, it is engaged by therestoring cam surface 7 and pushed back into the initial position. Thecam 5 is held in its initial position by means of a spring-loaded detentpin or the like 11, which engages in a groove 5a formed in the cam 5.

As already stated, the coils 6 and the restoring cam surfaces 7 are notpositioned in a row but staggered relative to each other on theperiphery of the cam drum 3, and a compact form of construction beingobtained thereby for this initiating device.

The coils and restoring cam surface are arranged in four groups, eachgroup on a bridge element 12, for example one group for the first,fifth, ninth, 13th, 17th and 21st impression points. 0f the four bridgeelements 12 incorporated in the example of embodiment, only two areillustrated in the drawing. The staggered arrangement of the coils 6 onthe periphery of the cam drum 3 has the result that the so-called accessperiod for a specific numeral 2, Le. the time required on selection ofthe character for rotary displacement of the type drum to bring thecharacter which is to be printed to the impression point, is not of thesame magnitude at all impression points. For equalization of the accessperiods, the type discs are also arranged in groups and positionedperipherally staggered on the spindle of the type drum.

As apparent from the drawing, the coils 6 are distributed on theperiphery of the cam drum 3, in such manner that the same maysimultaneously actuate a second striker system 110 respectively a secondprinting mechanism. The striker segments 110 of the second strikersystem are turnably mounted on a pin 115 and held in their initialpositions by springs 116 carried at one end by pin 117 against dampingelement 118.

For adaptation of the access periods, the type discs incorporated in thetype drum 101 in this printing mechanism are correspondingly installedin staggered arrangement.

We claim:

1. In a high-speed printer, in combination, a type drum rotatable aboutits axis, said type drum having on its periphery at least one set ofcharacters arranged circumferentially spaced from each othersubstantially in a plane normal to the axis of the drum; a cam drumrotatable in a predetermined direction about an axis substantiallyparallel to that of said type drum and in correlation to the rotation ofthe latter and including at least one set of cams circumferentiallyspaced from each other and each movable between an active position andan inactive position; at least one striker; means mounting said strikermovable in said plane toward and away from the periphery of said typedrum with a portion of said striker located in the path of a cam locatedin said active position so as to be engaged by the latter duringrotation of said cam drum and to be moved toward the periphery of saidtype drum so as to move a recording medium located between said strikerand the periphery of said type drum into engagement with a character;moving means cooperating with said cams to move a selected cam of saidset of cams from its inactive to said active position; and restoringmeans located in direction of rotation of said cam drum ahead of saidmoving means for moving any cam which is in said active position back toits inactive position, said restoring means comprising a stationary camface arranged to cooperate with a cam in active position to move thelatter to its inactive position.

' 2. A structure as defined in claim 1, wherein said striker comprises asegment pivotally mounted on said mounting means about an axissubstantially parallel to that of said type drum.

3. A structure as defined in claim 1, and including means for yieldablymaintaining said cams in said inactive position and comprising a springloaded detent means for each cam.

4. In a high-speed printer, in combination, a type drum rotatable aboutits axis and having on its periphery a plurality of sets of typecharacters, the type characters in each set being arrangedcircumferentially spaced from each other substantially in a plane normalto the axis of said drum, and the plurality of sets being arranged in aplurality of axially displaced planes; a cam drum rotatable in apredetermined direction about an axis substantially parallel to that ofsaid type drum and in correlation to the rotation of the latter andincluding a plurality of sets of cams. the cams of each set beingcircumferentially spaced from each other and said set of cams beingarranged in said cam drum axially displaced from each other, each cambeing movable in radial direction between an active position and aninactive position; a plurality of strikers; means mounting said strikersrespectively movable in said planes toward and away from the peripheryof said type drum with a portion of each striker located in the path ofa respective cam when the latter is in said active position so as to beengaged by the respective cam during rotation of said cam drum and to bemoved toward the periphery of said type drum so as to move a recordingmedium located between the engaged striker and the periphery of saidtype drum into engagement with a character; moving means cooperatingwith said cams to move a selected cam of said sets of cams from itsinactive to its active position; and restoring means located indirection of rotation of said cam drum ahead of said moving means formoving any cam which is in said active position back to its inactiveposition, said moving means and said restoring means for said sets ofcams are staggered about the periphery of said cam drum.

5. A structure as defined in claim 4, wherein said cam drum comprises aplurality of coaxial discs abutting against each other with opposite endfaces thereof, each of said discs being formed in each of said end facesthereof with a plurality of radially extending grooves for guidingadjacent sets of cams movable between said active and said inactiveposition.

6. A structure as defined in claim 4, and including a second pluralityof strikers arranged circumferentially spaced from said first mentionedplurality of strikers adjacent to the periphery of said cam drum and asecond type drum arranged for cooperation with said second plurality ofstrikers, said restoring means for each set of cams being located in thedirection of movement of said cam drum ahead and closely adjacent to therespective moving means.

